1. Field of the Invention
The present invention relates to a device for removal of condensate from a fluted drying cylinder.
2. Description of the Related Art
Known for solving the problem of evacuating the condensate accumulating in the interior of a steam-heated drying cylinder are already many different designs. The ultimate concern is to pass the condensate forming as the superheated steam introduced in the interior of the drying cylinder cools down to the outside (to a steam separator), in order to keep the inside wall of the drying cylinder, and thus the drying cylinder itself, as much as possible at a constant operating or working temperature. The superheated steam is supplied through a steam pipe situated coaxially to the bearing of the drying cylinder; the condensate itself passes via the condensate evacuation pipe to a collector and a hollow shaft mounted coaxially in the drying cylinder, whence the condensate is evacuated via a condensate discharge pipe which extends through the steam pipe or through the diametral end face of the drying cylinder.
The prior art relevant to "dewatering systems for fluted drying cylinders" includes three designs:
It is known to fix condensate collectors on the inside ribbing of the cylinder shell and to connect them to an inner hollow shaft. In the area of the hollow shaft, the connection is based on unique ball joint elements, and a length compensation element is provided toward the collector. In actual operation it has been demonstrated that the collector causes deformations of the cylinder shell. The result is a non-uniform and, as the case may be, incomplete dewatering, which ultimately may lead to a degraded paper quality.
Another known design comprises fastening the collector to the hollow shaft and supporting it on the covers of the drying cylinder; thus the cylinder is not in contact with the inside of the cylinder shell. This configuration has been found to be disadvantageous in that the position of the condensate pipes changes relative to the groove bottom, due to thermal expansion of the collector in transverse direction; the result again being a non-uniform and incomplete dewatering. Another difficulty with this design is that the bearing forces, or mass forces, of the collector burden the cylinder cover.
A third relevant concept is characterized in that the collectors are fixed only on the hollow shaft, making contact neither with the cylinder shell nor the cylinder covers. The dewatering itself takes place by way of extended dewatering tubes which protrude sideways from the collector, are fixed on the grooves of the cylinder shell and are adjustable relative to the groove bottom.
Viewed in terms of function, this prior design meets its objective in which context it is particularly noted that the long dewatering tubes assure a spatial degree of freedom. The disadvantage of this design is that the dewatering tubes are very complex and thus expensive components.
A problem underlying the present invention consists in providing a device for evacuating condensate from a fluted drying cylinder, wherein the condensate evacuation pipes functioning as dewatering tubes allow a simpler and thus more low-cost manufacture.